1. Field of the Invention
The present invention relates to an organic light emitting display device and a method of fabricating the same, and more particularly, to an organic light emitting display device that includes a first electrode having a first metal layer, a second metal layer, and a third metal layer including a transparent conductive oxide layer, and a method of fabricating the same.
2. Description of the Related Art
In general, an organic light emitting display device includes a first electrode, an organic layer disposed on the first electrode and having an organic emission layer, and a second electrode disposed on the organic layer. In the organic light emitting display device, when a voltage is applied between the first and second electrodes, holes are injected from the first electrode into the organic layer, and electrons are injected from the second electrode into the organic layer. The holes and electrons injected into the organic layer are recombined in the organic emission layer and form excitons. When the excitons transition from an excited state to a ground state, light is emitted.
In such an organic light emitting display device, the first electrode is a reflection type, i.e., is formed to reflect light, and the second electrode is a transmission type, i.e., is formed to transmit light. Thus, a top-emission organic light emitting display device that emits light from the organic emission layer toward the second electrode may be fabricated.
Compared to widely commercialized liquid crystal displays (LCDs), the organic light emitting display device, an active emissive display device, has advantages of wide viewing angle, high picture quality, and motion picture display capability due to a 30,000 times fast response speed. The organic light emitting display device has a stacked structure having enhanced luminous efficiency due to increased recombination of electrons and holes.
In the organic light emitting display devices, while a conductive material having an excellent reflection property and an appropriate work function is suitable for the reflection-type first electrode, it appears that no single applicable material has both of these properties. Accordingly, the reflection-type first electrode may be formed in a multi-layer structure.
FIG. 1 is a schematic cross-sectional view illustrating a method of fabricating a conventional organic light emitting display device including a reflection-type first electrode.
Referring to FIG. 1, a substrate 100 on which a reflective layer 110a and a transparent conductive layer 110b are sequentially stacked is provided. A thin film transistor and a capacitor may be included between the substrate 100 and the reflective layer 110a. 
Here, the reflective layer 110a may include aluminum (Al) which has an excellent reflection property, and the transparent conductive layer 110b may be formed of indium tin oxide (ITO) or indium zinc oxide (IZO) which has a high work function.
Subsequently, a photoresist pattern is formed on the transparent conductive layer 110b, and the transparent conductive layer 110b and the reflective layer 110a are sequentially etched using the photoresist pattern as a mask. After etching, the photoresist pattern is removed using a stripping solution so as to complete a first electrode 110 including the reflective layer 110a and the transparent conductive layer
Then, an organic layer 120 including an organic emission layer is formed on the first electrode 110, and a second electrode 130 is formed on the organic layer, thereby completing an organic light emitting display device.
However, Al and ITO, which are used respectively for a reflective layer and a transparent conductive layer in a first electrode of a conventional organic light emitting display device, are impossible or extremely difficult to blanket-etch due to a galvanic effect, and thus a fabrication process of the organic light emitting display device is complicated. Also, since silver (Ag), which can be blanket-etched along with ITO and has an excellent reflection property, does not adhere well to a planarization layer, a very gentle cleaning process is performed and many particles remain, which is a leading cause of dark pixel defects.